Benjamin will receive an MRI tomorrow, according to Mike Florio of ProFootballTalk.com.
The receiver was carted off the field after a 20-yard reception, and the team officially ruled him out in the first quarter.
After starting the season with the Carolina Panthers, Benjamin was surprisingly dealt to the Bills before the NFL's trade deadline on Oct. 31. He is having a solid statistical season with 517 receiving yards and two touchdowns on 35 receptions entering the day.
Per Pro Football Focus, at the time of the trade, Benjamin's 79.1 overall grade this season was better than any receiver on the Bills roster.
Injuries are a concern for Benjamin, who missed the entire 2015 season with a torn ACL suffered during a joint practice with the Miami Dolphins. He injured the same knee in Week 3 this season against the New Orleans Saints, though an MRI showed no structural damage, and he's yet to miss a game so far in 2017.
Buffalo has been a surprise playoff contender in the AFC, and losing one of its best playmakers will force someone else to fill in. The Bills will rely on Jordan Matthews, Zay Jones and Andre Holmes to make plays until Benjamin is able to return.